This research study is attempting to add to the limited existing body of literature regarding vancomycin dosing in obese patients. The investigators hypothesize that optimizing the initial or loading vancomycin dose that obese patients receive will decrease the time to target concentrations. For this study, obese adult patients will be randomized to receive either 1) a loading dose of 20 mg/kg with a maximum dose up to 2,000mg OR 2) a loading dose of 20 mg/kg with a maximum dose of up to 4,000mg. The study's primary aim is to determine differences in the time needed to achieve target vancomycin concentrations and the occurrence of adverse events.